SCIENCE

Cannabis exposure in adolescents and young adults is not associated with any significant long-term detrimental effects on cognitive performance, according to a systematic literature review published today in the journal JAMA Psychiatry.

Investigators affiliated with the University of Pennsylvania, Perelman School of Medicine and with the Children’s Hospital of Pennsylvania reviewed data from 69 separate studies published between 1973 and 2017 involving 8,727 subjects (2,152 frequent or heavy users and 6,575 controls). Researchers reported no significant long-term deficits in memory, attention, or other aspects of cognitive functioning that could be independently attributed to cannabis use, regardless of subjects age of initiation. These findings are in contrast to similar studies assessing the impact of alcohol use and other controlled substances on cognition, which “have shown medium to large effect sizes.”

Authors concluded: “Associations between cannabis use and cognitive functioning in cross-sectional studies of adolescents and young adults are small and may be of questionable clinical importance for most individuals. Furthermore, abstinence of longer than 72 hours diminishes cognitive deficits associated with cannabis use. [R]esults indicate that previous studies of cannabis youth may have overstated the magnitude and persistence of cognitive deficits associated with marijuana use.”

Commenting on the study’s findings, NORML Deputy Director Paul Armentano said: “These conclusions are consistent with those of prior studies – in particular, recent longitudinal twin studies reporting that cannabis use is not independently associated with any residual change in intelligence quotient or executive function. These findings, combined with other recent studies reporting that cannabis exposure appears to have minimal adverse impact on brain morphology — particularly when compared to the dramatic effects of alcohol —dispute the long-standing ‘stoner-stupid’ stereotype. These findings should help to assuage fears that cannabis’ acute effects on behavior may persist long after drug ingestion, or that they may pose greater potential risks to the developing brain.”

The enactment of marijuana legalization laws is associated with a significant reduction in the number of opioids prescribed and filled, according to a pair of studies published online today in the journal JAMA Internal Medicine.

In the first study, investigators from the University of Kentucky and Emory University assessed the association between medical and adult-use marijuana laws with opioid prescribing rates and spending among Medicaid enrollees. They reported:

“State implementation of medical marijuana laws was associated with a 5.88 percent lower rate of opioid prescribing. Moreover, the implementation of adult-use marijuana laws, which all occurred in states with existing medical marijuana laws, was associated with a 6.38 percent lower rate of opioid prescribing. … [T]he further reductions in opioid prescribing associated with the newly implemented adult-use marijuana laws suggest that there were individuals beyond the reach of medical marijuana laws who may also benefit from using marijuana in lieu of opioids. Our finding that the lower opioid prescribing rates associated with adult-use marijuana laws were pronounced in Schedule II opioids further suggest that reaching these individuals may have greater potential to reduce the adverse consequences, such as opioid use disorder and overdose.”

The full text of the study, “Association of Medical and Adult-Use Marijuana Laws With Opioid Prescribing for Medicaid Enrollees,” is available here.

In the second study, University of Georgia researchers evaluated the association between the enactment of medical cannabis access laws and opioid prescribing patterns under Medicare Part D. They reported:

“This longitudinal analysis of Medicare Part D found that prescriptions filled for all opioids decreased by 2.11 million daily doses per year from an average of 23.08 million daily doses per year when a state instituted any medical cannabis law. Prescriptions for all opioids decreased by 3.742 million daily doses per year when medical cannabis dispensaries opened. … Combined with previously published studies suggesting cannabis laws are associated with lower opioid mortality, these findings further strengthen arguments in favor of considering medical applications of cannabis as one tool in the policy arsenal that can be used to diminish the harm of prescription opioids.”

The full text of the study, “Association Between US State Medical Cannabis Laws and Opioid Prescribing in the Medicare Part D Population,” is available here.

The enactment of adult use marijuana regulation in Colorado and Washington is not independently linked to an increase in traffic fatalities, according to a study published this week by the National Bureau of Economic Research.

Investigators at the University of Oregon compared traffic accident outcomes in Colorado and Washington following legalization to other states with similar pre-legalization economic and traffic trends. They reported, “We find that states that legalized marijuana have not experienced significantly different rates of marijuana- or alcohol-related traffic fatalities relative to their synthetic controls.”

Authors concluded, “In summary, the similar trajectory of traffic fatalities in Washington and Colorado relative to their synthetic control counterparts yield little evidence that the total rate of traffic fatalities has increased significantly as a consequence of recreational marijuana legalization.”

The study’s findings are similar to those of a 2017 study published in The American Journal of Public Health which reported, “Three years after recreational marijuana legalization, changes in motor vehicle crash fatality rates for Washington and Colorado were not statistically different from those in similar states without recreational marijuana legalization.”

A 2016 study reported that the enactment of medical cannabis legislation is associated with an immediate decline in traffic fatalities among younger drivers.

Full text of the study, “Early evidence on recreational marijuana legalization and traffic fatalities” is available from the National Bureau of Economic Research. NORML’s fact-sheets on cannabis, psychomotor performance, and accident risk is online here.

Cannabis therapy mitigates symptoms of the chronic pain condition fibromyalgia and is associated with a reduction in the use of other prescription drugs, according to clinical data published online ahead of print in the Journal of Clinical Rheumatology. An estimated 3 to 6 million Americans are afflicted by fibromyalgia, which is often poorly controlled by standard pain medications.

Israeli investigators assessed the safety and efficacy of inhaled cannabis in a cohort of 26 patients with fibromyalgia. They reported that medical cannabis treatment “was associated with significant favorable outcomes in every item evaluated,” such as reductions in pain and increases in energy.

Most patients also reduced their use of conventional prescription drugs, such as opiates and benzodiazepines, during the trial period. Nearly half of the participants (46 percent) reduced their prescription drug intake by more than 50 percent during the study. Several patients were also able to return to work following the initiation of cannabis therapy.

Researchers concluded, “Medical cannabis treatment had a significant favorable effect on patients with fibromyalgia, with few adverse effects.”

Prior trials evaluating the use of either whole-plant cannabis or synthetic cannabinoids have similarly shown efficacy in patients with the disease. A summary of these prior studies is available here.

The abstract of the study, “Medical cannabis for the treatment of fibromyalgia,” is online here.

Patients routinely reduce or eliminate their use of prescription opiates following the use of medical cannabis; two recently published studies reaffirm this relationship.

In the first study, published by the Minnesota Department of Health, investigators assessed the prescription drug use patterns of 2,245 intractable pain patients participating in the state’s medical cannabis access program. Among those patients known to be taking opiates for pain upon enrollment in the program, 63 percent “were able to reduce or eliminate opioid usage after six months.” The findings are similar to those of registered patients in other states’ medical cannabis programs, including Illinois, Michigan, and New Mexico, among others.

In the second study, Israeli researchers assessed the safety and efficacy of cannabis in a cohort of over 1,200 cancer patients over a period of six months. Ninety-six percent of patients “reported an improvement in their condition.” Nearly half of respondents reported either decreasing or eliminating their use of opioids during the treatment period.

A third recently published clinical trial provides insight into explaining this relationship. Investigators from the United States and Australia and assessed the efficacy of inhaled cannabis and sub-therapeutic doses of oxycodone on experimentally-induced pain in a double-blind, placebo-controlled model. Researchers assessed subjects’ pain tolerance after receiving both substances separately or in concert with one another. While neither the administration of cannabis nor oxycodone alone significantly mitigated subjects’ pain, the combined administration of both drugs did so effectively.

Authors determined, “Both active cannabis and a low dose of oxycodone (2.5 mg) were sub-therapeutic, failing to elicit analgesia on their own; however, when administered together, pain responses … were significantly reduced, pointing to the opioid-sparing effects of cannabis.” They concluded, “Smoked cannabis combined with an ineffective analgesic dose of oxycodone produced analgesia comparable to an effective opioid analgesic dose without significantly increasing cannabis’s abuse liability.”

The new studies add to the growing body of research finding that cannabis access is associated with reduced rates of opioid use and abuse, opioid-related hospitalizations, opioid-related traffic fatalities, opioid-related drug treatment admissions, and opioid-related overdose deaths.

Additional information regarding the association between cannabis and opioids is available from NORML’s fact-sheet here.